Special fabric propeller



Dec. 29 1925.

N. S. CLAY SPECIAL FABRIC PRORELLER Filed Sept. 20 1923 I nlml ilmlnl. l"|"l" w ME INVENTOR Nob/e SIC/0] ATTORNEY Patented Dec. 29, 192 5.

UNITED STATES PATENT OFFICE.

NOBLE S. CLAY, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC 8:; MANUFACTURING COMPANY, A CORPORATION OLE PENN SYLVANIA.

SPECIAL FABRIC PBCPELLER.

Application filedseptenrber 20, 1923. Serial No. 663,739.

citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement 7 in Special Fabric Propellers, of which the following is'a specification.

. My invention relates to propellers and more particularly to special fabric propellers for air craft.

Heretofore, various types of wooden propellers have been used, but it is becoming increasingly difiicult to obtain the proper kind and grade of wood. The necessity of employing expert or skilled workmen, and the fact that wooden propellers warp and are subject to rapid wear, are important disadvantages. More recent developments have been to form a propeller from initially flexible material made rigid by theapplication of a binder which may be hardened,

, such as a phenolic condensation product.

In a process of this kind, the propeller is built up of laminations or layers of flexible material, pressed, molded or otherwise formed into the desired shape, such material being previously impregnated with a phenolic condensation product, so'that when the assembled layers are heated under pressure the entire structure is compacted and rendered hard and substantially insoluble and it acquires a high degree of strength and rigidity.

Even such laminated propellers made as described above have been found to possessdefects. Propellers of this type have more strength than is necessary, in a transverse direction and have beengknownto fail in the longitudinal direction. The strains and stresses set up by reason of centrifugal forces, bending and thrust moments and vibrations sometimes exceed the ultimate tensile strength of the material longitudinally.

My invention is intended to overcome the defects and disadvantages of previous structures as herein set forth, it being among theobjects thereof to provide a propeller which shall have a high degree of strength in the direction of greatest strain.

In practicing my invention, I employ a special filling material and a phenolic condensation product or other ibinder which hardens and becomes substantially, infusible and insoluble upon the application of composed of relatively small transverse cords or strands, and tightly twisted cords which are relatively stronger and more numerous than the other or transverse cords or strands and a binder which hardens and becomes substantially infusible and insoluble upon the application of heat. The tightly twisted cords are placed longitudinally of the propeller blade.

I have found it preferable, however, to employ laminations of loose flat twisted longitudinal cords or strands which are relatively larger and more numerous than the transverse strands and a phenolic condensation product or other binder, which hardens and becomes substantially, insoluble and infusible upon the application of heat. This material provides a propeller structure which is considerably stronger than that formed from the ordinary cord fabric.

In the accompanying drawing constituting a part hereof and in which like reference characters represent like parts,

Figure l is a plan view of a propeller con structed in accordance with my invention;

Fig. 2 is a sideelevational view there- Fig. 3 is a sectional view along the line IIIIII of Fig. 2;

Fig. 4 is a sectional view along the line IVIV Fig. 2: I Fig. 5,-is a sectional view along the line II-I I of Fig. l and shows the built up or laminated structure of the finished propeller, and

Fig.6 is an enlarged, fragmentary plan view of the special fabric utilized.

The propeller 1 is preferably formedof a series of preformed layers or laminations 2, as generally shown in Figures 1-5. The layers or laminations 2 may be of special fabric or woven material composed of a plurality of classes of strands, so cut or formed that when forming the propeller, some of the strands 3, of which may be tightly twist 4 which are placed substantially transverse The layers or laminations of special a fabric or woven material previously impregnated with a suitable binder are cut to the proper shapes and a suitable number thereof assembled in a mold. The cords 3 of each of the laminations 2 are substantially par.- allel to the axis'of the propeller. Heat and pressure are iapplied to consolidate thematerial and to form a dense, homogeneous mass. I

A propeller or other device embodying a special fabric or woven material of substantially the type herein described and a phenolic condensation product or other binder which hardens and becomes substantially infusi e and insoluble upon the application of he t, is superior to similar devices made heretofore. The use of larger andstronger strands or cords increase both the elastic limit and the ultimate strength in the direction of such cords without sacrificing any needed strength in other directions. A device, which is to be subjected to largestrainsand stresses in one direction with only minor stresses transversely to the said strains andstresses, when constructed'in accordance with my invention, will be considerably stronger than if made from ordinary fabric or other sheet material, particularly in the direction of maximum stresses.

Propellers employing the tightly twisted cord fabric, while having a little less strength transversely, are. approximately twice as strong longitudinally as those employing ordinary fabric used heretofore,

while 'propellers employing the special fab- .ric embodying flat, loosely twisted cords have 2 times the strength longitudinally of those employing ordinary fabric. The

- ultimate strength of the propellers embodying either of these special 'cord fabrics is approximately the same, but the elastic limit of the one employing the loosely twisted cords is about 50% greater than the 'one employing the tightly twisted cords, both however, being distinctl superior to propellers made by previously well-known methods. I

Obviously various changes in construction of my new propeller may be madewithin the scope of my invention. For instance, I may utilize a suitable number of classes of strands placed in difierent directions to provide increased strength in such directions. Other binders may 'be substituted for the phenolic condensation product described. Although I prefer to use this construction binder.

3.v A propeller comprising laminations of A a material having a plurality of classes of strands, one of which predominates, and a binder which hardens and becomes substantially insoluble and infusible upon the application of heat.

A propeller comprising laminations of a material having a plurality of classes of strands, one of which predominates, and a phenolic condensation product as a binder.

5. A propeller comprising a material having a plurality of classes 'of strands, the longitudinal strands of which predominate, and a phenolic condensation product as a binder.

A prop eller comprising a material having a plurality of classes of strands the longitudinal-strands of which predominate, and a binder which hardens and becomes substantially insoluble and infusible upon the a plication of heat. J

7. propeller comprising laminations of 'a material having a plurality of classes of strands, the longitudinal strands of which predominate, and a phenolic condensation product as a binder. J

8. A pro eller comprising laminations of a material havir'lg a plurglity of classes of strands, the longitudinalstrands of which predominate,'and a binder. which hardens and becomes substantially insoluble and infusible upon the applicationof heat.

. 9. A propeller comprising a material having a pluralityof classes of strands, the longitudinal strandsof' which are loose and,

flat twisted and substantially parallel to the longitudinal axis a binder.

having a plurality of classes of strands the longitudinal strands of which are loose and flat twisted and substantially parallel to the longitudinal axis of the propeller, and a binder which hardens and becomes substantially insoluble and infusible upon the application of heat.

11. A propeller comprising a materialhaving a plurality of classes of strands, the longitudinal strands of which are loose and flat twisted and substantially parallel to the longitudinal axis of the propeller, and a phenolic condensation product as a binder.

12. A pro eller comprising laminations of a material aving a plurality of classes of strands, the longitudinal strands of which are loose and flat twisted and substantially parallel to the longitudinal axis of the propeller, and a binder which hardens and becomes substantially insoluble and infusible upon the application of heat.

13. A propeller comprising a material having a plurality of classes of strands, the longitudinal strands of which are loose and flat twisted, and are substantilly parallel to the longitudinal .axis of the propeller and are relatively larger and more numerous than the transverse strands and a binder which hardens and becomes substantially insoluble and infusible upon the application of heat. r

14. A propeller comprising laminations of a material having a plurality of classes of strands, the longitudinal strands of which are loose and fiat twisted, are substantially parallel to the longitudinal axis of the propeller and are relatively larger and more numerous than the transverse strands, and a binder which hardens and becomessubstantially insoluble and infusible upon the application of heat.

15. A propeller comprising laminations of a material having a lurality of classes of strands the longitudlnal strands of which are loose and flat twisted, are substantially parallel to the longitudinal axis of the propeller and are relatively larger and more numerous than the transverse strands, and a phenolic condensation roduct as a binder.

In testimony whereo I have hereunto subscribed my name this 13th day of September 1923.

NOBLE S. CLAY.- 

